A tubular core assembly for winding or unwinding sheet material, such as newsprint or Rotogravure Print, wherein the opposed ends of an elongate cylindrical core are provided with inside diameter-reducing annular core insert members. The inside diameter-reducing annular core insert members are secured by a mechanical interlocking member to a central core body formed by multiple wraps of a paperboard material. The mechanical interlocking member includes at least one radially interlocking member secured to and extending radially at least partially through the central core member and the annular core insert member. Because of the mechanical interlocking relationship between the inside diameter-reducing annular core insert members and the central core body member, the inside diameter-reducing annular core insert members are secured to the central core body member in positive locking relationship.
